"If it’s dangerous in toothpaste, it should certainly not be in infant formula," says Friends of the Earth, who commissioned the tests. Read the full story here.

Environmental group Friends of the Earth (FoE) wants three popular brands of infant formula in Australia taken off the shelves, after they were found to contain potentially toxic nanoparticles.

According to reports by Channel Nine news, news.com.au, and the Sydney Morning Herald, the tests - conducted by an expert team in nanotechnology at Arizona State University - discovered three of seven samples of formula tested, contained potentially toxic 'needle-like' nano-hydroxyapatite particles.

In animal testing, these particles have been found to damage the livers and kidneys of rats.

Even though hydroxyapatite occurs naturally in bones, FoE say that when included in food, it is synthetically produced and "presents serious health concerns due to its very small size."

“Due to their very small size, nanoparticles have been demonstrated to be more likely than larger particles to enter cells, tissues and organs,” says the organisation. “They can be more chemically reactive and more bioactive than larger particles of the same chemicals.”

The three brands they've called out are Nestle NAN H.A. Gold 1, Nature's Way Kids Smart 1 and Heinz Nurture Original 1.

"Babies are particularly vulnerable to food safety risks since their immune systems are still developing," FoE said.

"Often infant formula is the only food an infant receives. FSANZ needs to immediately recall these products."

The group has also recommended that FSANZ should test all other baby formula brands on sale in Australia for hydroxyapatite or other banned substances, say news reports.

No real danger?

Despite the warning by FoE, FSANZ reassures consumers that the baby formula brands under question pose no risk to the health of little ones drinking it.

"Carers of infants should not be alarmed by this report or concerned about the safety of these products," they said in a statement on Sunday.

They also quote several Australian experts in their statement.

Here are some extracts of these quotes:

Adjunct Professor Andrew Bartholomaeus, consultant toxicologist, University of Canberra, University of Queensland.

"The Friends of the Earth slide deck presents the rather unexciting and facile observation that a food containing high levels of calcium and phosphate and undergoing a variety of processes during production has a small quantity of calcium phosphate crystals (Ca apatite).

"Regardless of the provenance of the observed material, calcium apatite is a normal human component of teeth and bones and small quantities of nanoparticulate deposits of this material can be found in normal human tissue.

"Calcium apatite is also soluble in acidic conditions so the small quantity of the material present in infant formula would dissolve into essential nutrients and cease to be nano...

"There is no evidence to indicate that nano dimensions of particulates are of themselves a risk to human health, and normal human breast milk is composed of a nano material (casein protein agglomerates)..."

Professor Ian Rae, expert on chemicals in the environment and Honorary Professorial Fellow in the Faculty of Arts at the University of Melbourne.

"This is a classical NANO SCARE. The clue that the investigators are pushing an agenda is in their repeated use of the phrase 'needle like' to describe the crystals of hydroxyapatite. It's a 'dog whistle' for 'you will be feeding your babies sharp objects if you use these products'.

"The truth is that these particles are the natural form of hydroxyapatite and they dissolve easily in the acids of the digestive system. Moreover, the particles are extremely small - much smaller than the diameter of a human hair - and they make up a tiny proportion of the products.

"The use of all that analytical chemical firepower might serve to over-awe the non-expert reader. Anyone who understands them and can assess the numbers will just ask 'so what?'."